A Publication of the Delta Stewardship Council

NRC Weighs in on Science in the November 2010 Draft Bay Delta Conservation Plan

The National Research Council (NRC) has finished its review of California’s Draft Bay Delta Conservation Plan (BDCP), and found it “scientifically lacking.”

The NRC, part of the National Academies (Science, Engineering, and Medicine), was requested by the U.S. Secretaries of the Interior and Commerce to convene a panel of experts to review the use of science and adaptive management in a working draft of the BDCP-a draft plan to conserve and restore habitat for species of concern while continuing to divert water for agricultural and drinking water use in central and southern California.

According to the NRC’s report released in May, BDCP is “incomplete and contains critical scientific gaps.”

For instance, the panel found that the effects analysis (a systematic, scientific look at the potential impacts of a proposed project on the species that the project will potentially affect) was still in preparation and absent from the draft of the Plan, “representing a critical gap in the science underlying the plan and the corresponding conservation actions.”

The panel also found that the purpose of BDCP is not clear, making it difficult “to properly understand, interpret, and review the science that underlies the plan.” The central issue, the report says, is that “although the plan states it is an application for the incidental take of listed species as a result of the proposed water diversion project, it also sets out the goals of providing a more reliable water supply for the state of California and protecting the Delta ecosystem.” Because different processes would be used to fulfill these different purposes, the panel concluded that it would be “difficult to evaluate the BDCP without clarification of the plan’s goals.”

As to the use of science in BDCP, the report states that “quantitative evaluation of the environmental stressors that impact species of interest, ideally using life-cycle models, would strengthen the BDCP.” For example, much of the analysis of the decline of smelt and salmonids in the Delta has focused on water operations, in particular the pumping of water from the south of the Delta for export to other regions. “However,” the report adds, “a variety of other environmental factors have potentially large effects on these fishes; and considerable uncertainties remain about the impact that different aspects of flow management in the Delta, especially management of the salinity of the water, have on their survival.”

Overall, the panel concluded that “the Bay Delta Conservation Plan is little more than a list of ecosystem restoration tactics and scientific efforts, with no coordinated strategy for reaching the goals of the plan.”

“The NRC report on the draft version of BDCP found the science to be lacking,” Lead Scientist Cliff Dahm said. “Clearer goals and completion of a well-designed and comprehensive effects analysis are key steps to improving the scientific basis for the plan.”